Mass defections from Britain’s political parties are rare, but not unprecedented. So far, they have not proved fatal to the party which lost the defectors, nor have they resulted in the formation of a new party with long-term viability.
In the 1880s the Liberal Party lost a significant group of its MPs when the Liberal Unionists split from the party, in opposition to Irish Home Rule. The Liberal Unionists eventually merged with the Conservative Party in 1912. In 1931 the Liberals lost 24 MPs to the newly-formed Liberal Nationals, whose diminished rump eventually merged with the Conservatives in the 1960s.
More recently, in the 1980s, the Labour Party lost a significant number of defectors to the newly-formed Social Democratic Party (SDP). So, how does the scale of defections to UKIP compare to the SDP split and how worried should the other parties be?
The SDP attracted a total of 28 sitting Labour MPs and one Conservative. UKIP so far has attracted 3 Conservative MPs. Bob Spink resigned from the Conservatives to support UKIP in 2008. He did not resign his seat to cause a by-election, but he was defeated at the following general election in 2010. Douglas Carswell and Mark Reckless both left the Conservatives this autumn to join UKIP and have resigned their seats to cause by-elections at Clacton and Rochester and Strood respectively. Douglas Carswell won a convincing victory at Clacton, but Rochester and Strood is regarded as a less UKIP-friendly constituency.
The SDP won a total of four by-elections - Crosby (November 1981), Glasgow Hillhead (March 1982), Portsmouth South (June 1984), Greenwich (February 1987). However, these were all newly-won seats. The only MP defecting to the SDP who resigned and re-contested his seat, Bruce Douglas-Mann, lost his by-election.
In terms of party membership, the SDP recorded 65,000 members at the end of 1981 compared to UKIP’s current figure of just under 40,000. In opinion polls the SDP peaked at 50.5%, compared to UKIP’s peak (so far) of 23%.
After disappointing general elections in alliance with the Liberals in 1983 (6 seats) and 1987 (5 seats), the SDP merged with the Liberal Party in 1988 to form the Liberal Democrats.
So, far the scale of Conservative to UKIP defections is much smaller than the Labour to SDP exodus. UKIP may, of course, attract more defectors, but the momentum seems to have stalled. Had UKIP had another defector lined up, the press briefing at the end of the Conservative Party conference would have been the occasion to reveal the person. Expectations were raised and dashed. Further potential defectors may now await the result of the Rochester and Strood by-election.
Overall then, does UKIP pose a threat to the existence of the Conservatives, or any other party? The three main parties have all been in existence for over 100 years. This does not guarantee that they will survive indefinitely, but it does mean that they all have experience of recovery from serious set-backs.
The Liberal Party was reduced to just 5 MPs at its lowest point in the 1950s, but since recovered to a peak of 63 MPs. The Labour Party fell from 288 seats in 1929 to just 52 in 1931, but in 1945 it won the election by a landslide. After the SDP split, the Labour Party recovered and in 1997 won an even bigger landslide than 1945. The Conservative Party lost half its seats in 1997, but became the largest single party again in 2010.
In October 1930 the Conservatives, under Stanley Baldwin – arguably the most comparable Conservative leader to David Cameron – rallied after losing a by-election at Paddington South to a right-wing candidate from the Empire Free Trade Crusade, backed by newspaper magnate Lord Beaverbrook. In the event this was to be the Empire Crusade’s only by-election victory. Whether UKIP’s crusade will get the party any further remains to be seen, but on current evidence, the likelihood of an SDP-scale split seems remote. Despite the shock of the Paddington South by-election defeat, the Conservatives went on to be in power continuously from 1931 to 1945 – but always in a coalition.
An earlier version of my article appeared on The Conversation http://bit.ly/1Eo1mc3